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超光速 3

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2R-1C模型；嵌入式系统；参数估计；非迭代方法；二次型 1

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Accounting for the uncertainties in the estimation of average shear wave velocity using – correlations

《结构与土木工程前沿（英文）》 2021年 第15卷 第5期   页码 1199-1208 doi: 10.1007/s11709-021-0749-1

摘要： Site-specific seismic hazard analysis is crucial for designing earthquake resistance structures, particularly in seismically active regions. Shear wave velocity ( V S) is a key parameter in such analysis, although the economy and other factors restrict its direct field measurement in many cases. Various V S–SPT– N correlations are routinely incorporated in seismic hazard analysis to estimate the value of V S. However, many uncertainties question the reliability of these estimated V S values. This paper comes up with a statistical approach to take care of such uncertainties involved in V S calculations. The measured SPT– N values from all the critical boreholes were converted into statistical parameters and passed through various correlations to estimate V S at different depths. The effect of different soil layers in the boreholes on the Vs estimation was also taken into account. Further, the average shear wave velocity of the top 30 m soil cover ( V S30) is estimated after accounting for various epistemic and aleatoric uncertainties. The scattering nature of the V S values estimated using different V S– N correlations was reduced significantly with the application of the methodology. Study results further clearly demonstrated the potential of the approach to eliminate various uncertainties involved in the estimation of V S30 using general and soil-specific correlations.

关键词： uncertainties     V S– N correlations     V S30     SPT data     statistical methodology    

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Estimation of power in low velocity vertical axis wind turbine

Sampath S. S.,Sawan SHETTY,Chithirai Pon Selvan M.

《机械工程前沿（英文）》 2015年 第10卷 第2期   页码 211-218 doi: 10.1007/s11465-015-0338-x

摘要：

The present work involves in the construction of a vertical axis wind turbine and the determination of power. Various different types of turbine blades are considered and the optimum blade is selected. Mechanical components of the entire setup are built to obtain maximum rotation per minute. The mechanical energy is converted into the electrical energy by coupling coaxially between the shaft and the generator. This setup produces sufficient power for consumption of household purposes which is economic and easily available.

关键词： wind turbine     shaft design     power generation     generator    

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Image analyses for video-based remote structure vibration monitoring system

Yang YANG,Xiong (Bill) YU

《结构与土木工程前沿（英文）》 2016年 第10卷 第1期   页码 12-21 doi: 10.1007/s11709-016-0313-6

摘要： Video-based vibration measurement is a cost-effective way for remote monitoring the health conditions of transportation and other civil structures, especially for situations where accessibility is restricted and does not allow installation of conventional monitoring devices. Besides, video-based system is global measurement. The technical basis of video-based remote vibration measurement system is digital image analysis. Comparison of the images allow the field of motion to be accurately delineated. Such information is important to understand the structure behaviors including the motion and strain distribution. This paper presents system and analyses to monitor the vibration velocity and displacement field. The performance is demonstrated on a testbed of model building. Three different methods (i.e., frame difference method, particle image velocimetry, and optical Flow Method) are utilized to analyze the image sequences to extract the feature of motion. The Performance is validated using accelerometer data. The results indicate that all three methods can estimate the velocity field of the model building, although the results can be affected by factors such as background noise and environmental interference. Optical flow method achieved the best performance among these three methods studied. With further refinement of system hardware and image processing software, it will be developed into a remote video based monitoring system for structural health monitoring of transportation infrastructure to assist the diagnoses of its health conditions.

关键词： structure health monitoring     velocity estimation     frame difference     PIV     optical-flow method    

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Prediction of the shear wave velocity

Amoroso SARA

《结构与土木工程前沿（英文）》 2014年 第8卷 第1期   页码 83-92 doi: 10.1007/s11709-013-0234-6

摘要： The paper examines the correlations to obtain rough estimates of the shear wave velocity from non-seismic dilatometer tests (DMT) and cone penetration tests (CPT). While the direct measurement of is obviously preferable, these correlations may turn out useful in various circumstances. The experimental results at six international research sites suggest that the DMT predictions of from the parameters (material index), (horizontal stress index), (constrained modulus) are more reliable and consistent than the CPT predictions from (cone resistance), presumably because of the availability, by DMT, of the stress history index .

关键词： horizontal stress index     shear wave velocity     flat dilatometer test     cone penetration test    

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High velocity impact of metal sphere on thin metallic plate using smooth particle hydrodynamics (SPH)

Hossein ASADI KALAMEH, Arash KARAMALI, Cosmin ANITESCU, Timon RABCZUK

《结构与土木工程前沿（英文）》 2012年 第6卷 第2期   页码 101-110 doi: 10.1007/s11709-012-0160-z

摘要： The modeling of high velocity impact is an important topic in impact engineering. Due to various constraints, experimental data are extremely limited. Therefore, detailed numerical simulation can be considered as a desirable alternative. However, the physical processes involved in the impact are very sophisticated; hence a practical and complete reproduction of the phenomena involves complicated numerical models. In this paper, we present a smoothed particle hydrodynamics (SPH) method to model two-dimensional impact of metal sphere on thin metallic plate. The simulations are applied to different materials (Aluminum, Lead and Steel); however the target and projectile are formed of similar metals. A wide range of velocities (300, 1000, 2000, and 3100 m/s) are considered in this study. The goal is to study the most sensitive input parameters (impact velocity and plate thickness) on the longitudinal extension of the projectile, penetration depth and damage crater.

关键词： smoothed particle hydrodynamics     high velocity impact     sensitivity analysis    

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Experimental study on velocity characteristics of recirculation zone in humid air non-premixed flame

GU Xin, ZANG Shusheng, GE Bing

《能源前沿（英文）》 2008年 第2卷 第2期   页码 140-144 doi: 10.1007/s11708-008-0037-y

摘要： To examine the effect of the flow field within the recirculation zone on flame structure, the characteristic velocity fields of methane/humid air flame in non-premixed combustion behind a disc bluff-body burner were experimentally studied by particle image velocimeter (PIV).The results show that two stagnation points exist on the centerline in the recirculation zone flame. However, the distance of the two stagnation points in humid air combustion shortens, and the minimal dimensionless velocity increases compared with the conventional non-humid air combustion. In addition, the positional curves of the minimal velocities can be partitioned into three phases representing three different flame patterns. The analysis of axial minimal velocities on the centerline and their positions under different co-flow air velocity conditions reveals that fuel-to-air velocity ratio is the crucial parameter that governs humid air combustion flame characteristics.

关键词： distance     bluff-body     fuel-to-air velocity     stagnation     parameter    

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definition of metabolic dysfunction-associated fatty liver disease with elevated brachial-ankle pulse wave velocity

《医学前沿（英文）》 2022年 第16卷 第5期   页码 714-722 doi: 10.1007/s11684-021-0888-8

摘要： A new definition of metabolic dysfunction-associated fatty liver disease (MAFLD) has recently been proposed. We aim to examine the associations of MAFLD, particularly its discordance from non-alcoholic fatty liver disease (NAFLD), with the progression of elevated brachial-ankle pulse wave velocity (baPWV) and albuminuria in a community-based study sample in Shanghai, China. After 4.3 years of follow-up, 778 participants developed elevated baPWV and 499 developed albuminuria. In comparison with the non-MAFLD group, the multivariable adjusted odds ratio (OR) of MAFLD group for new-onset elevated baPWV was 1.25 (95% confidence interval (CI) 1.01–1.55) and 1.35 (95% CI 1.07–1.70) for albuminuria. Participants without NAFLD but diagnosed according to MAFLD definition were associated with higher risk of incident albuminuria (OR 1.77; 95% CI 1.07–2.94). Patients with MAFLD with high value of hepamet fibrosis score or poor-controlled diabetes had higher risk of elevated baPWV or albuminuria. In conclusion, MAFLD was associated with new-onset elevated baPWV and albuminuria independently of body mass index, waist circumference, and hip circumference. Individuals without NAFLD but diagnosed as MAFLD had high risk of albuminuria, supporting that MAFLD criteria would be practical for the evaluation of long-term risk of subclinical atherosclerosis among fatty liver patients.

关键词： metabolic dysfunction-associated fatty liver disease     non-alcoholic fatty liver disease     fibrosis score     brachial-ankle pulse wave velocity     albuminuria    

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Theoretical study of failure in composite pressure vessels subjected to low-velocity impact and internal

Roham RAFIEE, Hossein RASHEDI, Shiva REZAEE

《结构与土木工程前沿（英文）》 2020年 第14卷 第6期   页码 1349-1358 doi: 10.1007/s11709-020-0650-3

摘要： A theoretical solution is aimed to be developed in this research for predicting the failure in internally pressurized composite pressure vessels exposed to low-velocity impact. Both in-plane and out-of-plane failure modes are taken into account simultaneously and thus all components of the stress and strain fields are derived. For this purpose, layer-wise theory is employed in a composite cylinder under internal pressure and low-velocity impact. Obtained stress/strain components are fed into appropriate failure criteria for investigating the occurrence of failure. In case of experiencing any in-plane failure mode, the evolution of damage is modeled using progressive damage modeling in the context of continuum damage mechanics. Namely, mechanical properties of failed ply are degraded and stress analysis is performed on the updated status of the model. In the event of delamination occurrence, the solution is terminated. The obtained results are validated with available experimental observations in open literature. It is observed that the sequence of in-plane failure and delamination varies by increasing the impact energy.

关键词： composite pressure vessel     low-velocity impact     failure     theoretical solution     progressive damage modeling    

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Intelligent algorithm for optimal meter placement and bus voltage estimation in ring main distribution

L. RAMESH, N. CHAKRABORTY, S. P. CHOWDHURY

《能源前沿（英文）》 2012年 第6卷 第1期   页码 47-56 doi: 10.1007/s11708-011-0159-5

摘要： The advancement in power distribution system poses a great challenge to power engineering researchers on how to best monitor and estimate the state of the distribution network. This paper is executed in two stage processes. The first stage is to identify the optimal location for installation of monitoring instrument with minimal investment cost. The second stage is to estimate the bus voltage magnitude, where real time measurement is conducted and measured through identified meter location which is more essential for decision making in distribution supervisory control and data acquisition system (DSCADA). The hybrid intelligent technique is applied to execute the above two algorithms. The algorithms are tested with institute of electrical and electronics engineers (IEEE) and Tamil Nadu electricity board (TNEB) benchmark systems. The simulated results proves that the swarm tuned artificial neural network (ANN) estimator is best suited for accurate estimation of voltage with different noise levels.

关键词： artificial intelligence     power distribution control     state estimation    

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An operating state estimation model for integrated energy systems based on distributed solution

Dengji ZHOU, Shixi MA, Dawen HUANG, Huisheng ZHANG, Shilie WENG

《能源前沿（英文）》 2020年 第14卷 第4期   页码 801-816 doi: 10.1007/s11708-020-0687-y

摘要： In view of the disadvantages of the traditional energy supply systems, such as separate planning, separate design, independent operating mode, and the increasingly prominent nonlinear coupling between various sub-systems, the production, transmission, storage and consumption of multiple energy sources are coordinated and optimized by the integrated energy system, which improves energy and infrastructure utilization, promotes renewable energy consumption, and ensures reliability of energy supply. In this paper, the mathematical model of the electricity-gas interconnected integrated energy system and its state estimation method are studied. First, considering the nonlinearity between measurement equations and state variables, a performance simulation model is proposed. Then, the state consistency equations and constraints of the coupling nodes for multiple energy sub-systems are established, and constraints are relaxed into the objective function to decouple the integrated energy system. Finally, a distributed state estimation framework is formed by combining the synchronous alternating direction multiplier method to achieve an efficient estimation of the state of the integrated energy system. A simulation model of an electricity-gas interconnected integrated energy system verifies the efficiency and accuracy of the state estimation method proposed in this paper. The results show that the average relative errors of voltage amplitude and node pressure estimated by the proposed distributed state estimation method are only 0.0132% and 0.0864%, much lower than the estimation error by using the Lagrangian relaxation method. Besides, compared with the centralized estimation method, the proposed distributed method saves 5.42 s of computation time. The proposed method is more accurate and efficient in energy allocation and utilization.

关键词： integrated energy system     state estimation     electricity-gas coupling energy system     nonlinear coupling     distributed solution    

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Bayes estimation of residual life by fusing multisource information

Qian ZHAO, Xiang JIA, Zhi-jun CHENG, Bo GUO

《工程管理前沿（英文）》 2018年 第5卷 第4期   页码 524-532 doi: 10.15302/J-FEM-2018034

摘要：

Residual life estimation is essential for reliability engineering. Traditional methods may experience difficulties in estimating the residual life of products with high reliability, long life, and small sample. The Bayes model provides a feasible solution and can be a useful tool for fusing multisource information. In this study, a Bayes model is proposed to estimate the residual life of products by fusing expert knowledge, degradation data, and lifetime data. The linear Wiener process is used to model degradation data, whereas lifetime data are described via the inverse Gaussian distribution. Therefore, the joint maximum likelihood (ML) function can be obtained by combining lifetime and degradation data. Expert knowledge is used according to the maximum entropy method to determine the prior distributions of parameters, thereby making this work different from existing studies that use non-informative prior. The discussion and analysis of different types of expert knowledge also distinguish our research from others. Expert knowledge can be classified into three categories according to practical engineering. Methods for determining prior distribution by using the aforementioned three types of data are presented. The Markov chain Monte Carlo is applied to obtain samples of the parameters and to estimate the residual life of products due to the complexity of the joint ML function and the posterior distribution of parameters. Finally, a numerical example is presented. The effectiveness and practicability of the proposed method are validated by comparing it with residual life estimation that uses non-informative prior. Then, its accuracy and correctness are proven via simulation experiments.

关键词： residual life estimation     Bayes model     linear Wiener process    

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Thermal degradation kinetics and lifetime estimation for polycarbonate/polymethylphenylsilsesquioxane

Jiangbo WANG, Zhong XIN

《化学科学与工程前沿（英文）》 2009年 第3卷 第2期   页码 167-171 doi: 10.1007/s11705-009-0006-y

摘要： The thermal degradation behaviors of polycarbonate/polymethylphenylsilsesquioxane (FRPC) composites were investigated by thermogravimetric analysis (TGA) under isothermal conditions in nitrogen atmosphere. The isothermal kinetics equation was used to describe the thermal degradation process. The results showed that activation energy ( ), in the case of isothermal degradation, was a quick increasing function of conversion (α) for polycarbonate (PC) but was a strong and decreasing function of conversion for FRPC. Under the isothermal condition, the addition of polymethylphenylsilsesquioxane (PMPSQ) retardanted the thermal degradation and enhanced the thermal stability of PC during the early and middle stages of thermal degradation. It also indicated a possible existence of a difference in nucleation, nuclei growth, and gas diffusion mechanism in the thermal degradation process between PC and FRPC. Meanwhile, the addition of PMPSQ influenced the lifetime of PC, but the composite still met the demand in manufacturing and application.

关键词： polycarbonate     polymethylphenylsilsesquioxane     thermal degradation kinetics     activation energy     lifetime    

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Topology optimization of piezoelectric bi-material actuators with velocity feedback control

Mariana MORETTI, Emílio C. N. SILVA

《机械工程前沿（英文）》 2019年 第14卷 第2期   页码 190-200 doi: 10.1007/s11465-019-0537-y

摘要： In recent years, the new technologies and discoveries on manufacturing materials have encouraged researchers to investigate the appearance of material properties that are not naturally available. Materials featuring a specific stiffness, or structures that combine non-structural and structural functions are applied in the aerospace, electronics and medical industry fields. Particularly, structures designed for dynamic actuation with reduced vibration response are the focus of this work. The bi-material and multifunctional concepts are considered for the design of a controlled piezoelectric actuator with vibration suppression by means of the topology optimization method (TOM). The bi-material piezoelectric actuator (BPEA) has its metallic host layer designed by the TOM, which defines the structural function, and the electric function is given by two piezo-ceramic layers that act as a sensor and an actuator coupled with a constant gain active velocity feedback control (AVFC). The AVFC, provided by the piezoelectric layers, affects the structural damping of the system through the velocity state variables readings in time domain. The dynamic equation analyzed throughout the optimization procedure is fully elaborated and implemented. The dynamic response for the rectangular four-noded FE analysis is obtained by the Newmark’s time-integration method, which is applied to the physical and the adjoint systems, given that the adjoint formulation is needed for the sensitivity analysis. A gradient-based optimization method is applied to minimize the displacement energy output measured at a predefined degree-of-freedom of the BPEA when a transient mechanical load is applied. Results are obtained for different control gain values to evaluate their influence on the final topology.

关键词： topology optimization method     bi-material piezoactuator     active velocity feedback control     time-domain transient analysis     host structure design     vibration suppression    

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seismic liquefaction and performing parametric sensitivity analysis: Considering cumulative absolute velocity

Nima PIRHADI, Xiaowei TANG, Qing YANG, Afshin ASADI, Hazem Samih MOHAMED

《结构与土木工程前沿（英文）》 2021年 第15卷 第2期   页码 506-519 doi: 10.1007/s11709-021-0677-0

摘要： Lateral displacement due to liquefaction ( ) is the most destructive effect of earthquakes in saturated loose or semi-loose sandy soil. Among all earthquake parameters, the standardized cumulative absolute velocity ( ) exhibits the largest correlation with increasing pore water pressure and liquefaction. Furthermore, the complex effect o fine content( ) at different values has been studied and demonstrated. Nevertheless, these two contexts have not been entered into empirical and semi-empirical models to predict This study bridges this gap by adding to the data set and developing two artificial neural network (ANN) models. The first model is based on the entire range of the parameters, whereas the second model is based on the samples with values that are less than the 28% critical value. The results demonstrate the higher accuracy of the second model that is developed even with less data. Additionally, according to the uncertainties in the geotechnical and earthquake parameters, sensitivity analysis was performed via Monte Carlo simulation (MCS) using the second developed ANN model that exhibited higher accuracy. The results demonstrated the significant influence of the uncertainties of earthquake parameters on predicting

关键词： lateral spreading displacement     cumulative absolute velocity     fine content     artificial neural network     sensitivity analysis     Monte Carlo simulation    

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超光速研究中的几个理论问题

黄志洵,耿天明

《中国工程科学》 2007年 第9卷 第4期   页码 6-17

摘要：

宇宙早期的强子时期，光速比c大，实际上可达v＝75c。故光速随时间缓慢减小，从v降低到今天的值（c）。另一方面，根据对128个类星体吸收线的测量，在过去的6～12Ga期间，精细结构常数α平均增大了6×10－6，科学家们认为可能是光速变化造成的。对上述效应进行研究以了解宇宙的过去是有趣的。还深入讨论了超光速研究中的一些问题———微观粒子速度的定义，引力速度，量子纠缠态作用速度以及超距作用。对这些概念有了更准确的理解。

关键词： 可变光速     超光速     微观粒子速度     引力速度     量子纠缠态作用速度     超距作用    

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标题 作者 时间 类型 操作

Accounting for the uncertainties in the estimation of average shear wave velocity using – correlations

期刊论文

Estimation of power in low velocity vertical axis wind turbine

Sampath S. S.,Sawan SHETTY,Chithirai Pon Selvan M.

期刊论文

Image analyses for video-based remote structure vibration monitoring system

Yang YANG,Xiong (Bill) YU

期刊论文

Prediction of the shear wave velocity

Amoroso SARA

期刊论文

High velocity impact of metal sphere on thin metallic plate using smooth particle hydrodynamics (SPH)

Hossein ASADI KALAMEH, Arash KARAMALI, Cosmin ANITESCU, Timon RABCZUK

期刊论文

Experimental study on velocity characteristics of recirculation zone in humid air non-premixed flame

GU Xin, ZANG Shusheng, GE Bing

期刊论文

definition of metabolic dysfunction-associated fatty liver disease with elevated brachial-ankle pulse wave velocity

期刊论文

Theoretical study of failure in composite pressure vessels subjected to low-velocity impact and internal

Roham RAFIEE, Hossein RASHEDI, Shiva REZAEE

期刊论文

Intelligent algorithm for optimal meter placement and bus voltage estimation in ring main distribution

L. RAMESH, N. CHAKRABORTY, S. P. CHOWDHURY

期刊论文

An operating state estimation model for integrated energy systems based on distributed solution

Dengji ZHOU, Shixi MA, Dawen HUANG, Huisheng ZHANG, Shilie WENG

期刊论文

Bayes estimation of residual life by fusing multisource information

Qian ZHAO, Xiang JIA, Zhi-jun CHENG, Bo GUO

期刊论文

Thermal degradation kinetics and lifetime estimation for polycarbonate/polymethylphenylsilsesquioxane

Jiangbo WANG, Zhong XIN

期刊论文

Topology optimization of piezoelectric bi-material actuators with velocity feedback control

Mariana MORETTI, Emílio C. N. SILVA

期刊论文

seismic liquefaction and performing parametric sensitivity analysis: Considering cumulative absolute velocity

Nima PIRHADI, Xiaowei TANG, Qing YANG, Afshin ASADI, Hazem Samih MOHAMED

期刊论文

超光速研究中的几个理论问题

黄志洵,耿天明

期刊论文